/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.solr.search;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.search.*;
import org.apache.solr.common.params.SolrParams;
import org.apache.solr.common.util.NamedList;
import org.apache.solr.core.SolrConfig;
import org.apache.solr.request.SolrQueryRequest;
import org.apache.solr.search.function.*;

import java.io.IOException;
import java.util.Map;

/**
 * Create a range query over a function. <br>
 * Other parameters: <br>
 * <code>l</code>, the lower bound, optional) <br>
 * <code>u</code>, the upper bound, optional) <br>
 * <code>incl</code>, include the lower bound: true/false, optional,
 * default=true <br>
 * <code>incu</code>, include the upper bound: true/false, optional,
 * default=true <br>
 * Example: <code>{!frange l=1000 u=50000}myfield</code> <br>
 * Filter query example:
 * <code>fq={!frange l=0 u=2.2}sum(user_ranking,editor_ranking)</code>
 */
public class FunctionRangeQParserPlugin extends QParserPlugin {
	public static String NAME = "frange";

	public void init(NamedList args) {
	}

	@Override
	public QParser createParser(String qstr, SolrParams localParams,
			SolrParams params, SolrQueryRequest req) {
		return new QParser(qstr, localParams, params, req) {
			ValueSource vs;
			String funcStr;

			@Override
			public Query parse() throws ParseException {
				funcStr = localParams.get(QueryParsing.V, null);
				Query funcQ = subQuery(funcStr, FunctionQParserPlugin.NAME)
						.getQuery();
				if (funcQ instanceof FunctionQuery) {
					vs = ((FunctionQuery) funcQ).getValueSource();
				} else {
					vs = new QueryValueSource(funcQ, 0.0f);
				}

				String l = localParams.get("l");
				String u = localParams.get("u");
				boolean includeLower = localParams.getBool("incl", true);
				boolean includeUpper = localParams.getBool("incu", true);

				// TODO: add a score=val option to allow score to be the value
				ValueSourceRangeFilter rf = new ValueSourceRangeFilter(vs, l,
						u, includeLower, includeUpper);
				FunctionRangeQuery frq = new FunctionRangeQuery(rf);
				return frq;
			}
		};
	}

}

// This class works as either a normal constant score query, or as a PostFilter
// using a collector
class FunctionRangeQuery extends SolrConstantScoreQuery implements PostFilter {
	final ValueSourceRangeFilter rangeFilt;

	public FunctionRangeQuery(ValueSourceRangeFilter filter) {
		super(filter);
		this.rangeFilt = filter;
	}

	public DelegatingCollector getFilterCollector(IndexSearcher searcher) {
		Map fcontext = ValueSource.newContext();
		return new FunctionRangeCollector(fcontext);
	}

	class FunctionRangeCollector extends DelegatingCollector {
		final Map fcontext;
		ValueSourceScorer scorer;
		int maxdoc;

		public FunctionRangeCollector(Map fcontext) {
			this.fcontext = fcontext;
		}

		@Override
		public void collect(int doc) throws IOException {
			if (doc < maxdoc && scorer.matches(doc)) {
				delegate.collect(doc);
			}
		}

		@Override
		public void setNextReader(IndexReader reader, int docBase)
				throws IOException {
			maxdoc = reader.maxDoc();
			DocValues dv = rangeFilt.getValueSource().getValues(fcontext,
					reader);
			scorer = dv.getRangeScorer(reader, rangeFilt.getLowerVal(),
					rangeFilt.getUpperVal(), rangeFilt.isIncludeLower(),
					rangeFilt.isIncludeUpper());
			super.setNextReader(reader, docBase);
		}
	}
}
